Process for the manufacture of magnesium aluminosilicate for medical uses



United States Patent Int. Cl. C01f /00, %/00; C01b 33/28 U.S. Cl. 23315 5 Claims ABSTRACT OF THE DISCLOSURE A novel magnesium aluminosilicate of the following structure:

to be used as an antacid for medical application, and a process for preparing the compound by reacting slurries containing equivalent amounts of freshly produced basic sodium magnesium silicate and dibasic aluminum silicate, under vigorous stirring, at temperatures ranging from normal to about 70 C., for several hours, allowing the precipitate formed to settle, withdrawing the supernatant liquid, and drying.

Magnesium aluminosilicate represented by the formula MgO -Al O -2SiO -xH O is widely used for the treatment of disorders of the digestive tract as an excellent antacid because of its strong neutralizing capacity and buffering effect, which is sustained fora long time since it is not absorbed. Moreover, it does not generate carbon dioxide, avoiding thus the discomfort of belching.

According to a known method for the manufacture of the magnesium aluminosilicate, having the above composition, magnesium salt is either reacted with sodium aluminosilicate or sodium silicate with diacidic magnesium aluminate, according to equations of illustrating the process as follows:

The products obtained by the processes described above are all magnesium complex salts of aluminosilicate, having the following chemical structure:

The above reactions take an extremely long time, a very large volume of water, and a great deal of labor for the completion and for the purification of the final reaction mixture in order to obtain the magnesium aluminosilicate of the said chemical structure shown, thus causing a serious bottleneck for its mass production.

It is therefore the object of the invention to provide a combination of aluminum, magnesium and silicon of a structure, which while being different from the mag- 3,523,764: Patented Aug. 11, 1970 nesium aluminosilicate hitherto in use, would not exhibit a change in antacid activity, and which could be made by a much simpler method.

The magnesium aluminosilicate of the invention is of a novel'structure in which magnesium is combined directly to the silicate base on the one hand and to the aluminum base on the other, whereas in the old structure magnesium is combined with both aluminosilicate complex ions.

The novel structure is therefore represented as follows:

MgO-SiO-OAl0SiO0AlO-zHzO The process of the present invention is to react while stirring, with or without heating, the equivalents of freshly produced basic magnesium sodium silicate and dibasic aluminum silicate by reacting aqueous solutions of caustic soda and sodium silicate, respectively, with an aqueous solution of a water-soluble magnesium salt and with an aqueous solution of a Water-soluble aluminum salt and or to react the equivalents of basic silicates having the same composition to be produced during the reaction process. In other word, the slurry corresponding to basic magnesium aluminum silicate can be obtained by adding an aqueous solution of sodium hydroxide, with stirring, to a water-soluble magnesium salt, equivalent to 1 mol of MgO; e.g. the solution of magnesium sulfate or magnesium chloride, etc., which react thereafter with an aqueous solution of sodium silicate equivalent to 1 mol of SiO so that the sum of Na O including Na O in sodium silicate esuivalent to 1 mol of S10 comes to 1.5 mols. The reaction as illustrated below.

The slurry corresponding to a composition of dibasic aluminum silicate can also be readily produced by adding, with stirring, an aqueous solution of sodium hydroxide to a water-soluble aluminum salt equivalent to 1 mol of A1 0 eg an aqueous solution of aluminum sulfate or aluminum chloride, with which is reacted an aqueous solution of sodium silicate equivalent to 1 mol of SiO so that the sum of Na O will be 3 mols including Na O contained in the sodium silicate corresponding to 1 mol of SiO see equations below.

Then, when mixing both slurries of basic silicates thus produced and reacting them while stirring with or without heating, hydrate of the novel magnesium aluminosilicate is synthetized that is the object of this invention.

In the meantime, when adding, with stirring, an aqueous solution of sodium hydroxide to the aqueous mixture of magnesium and aluminum salts referred to above, corresponding to 1 mol of MgO and A1 0 respectively, so that the sum of Na O comes to 4 mols including Na O in the sodium silicate equivalent to 2 mols of SiO followed by the addition of an aqueous solution of sodium silicate, corresponding to 2 mols of SiO the slurries having the compositions corresponding to basic sodium magnesium silicate and to dibasic aluminum silicate respectively are simultaneously produced and both of them are then condensed for reaction on the spot.

easy, and further since the sodium hydroxide produced as by-product at the last step of the condensation can 3 4 be utilized for the neutralization in the first part of the not only to complete the reaction, but also to purify the reaction, the material cost can be cut down considerably reaction product. On the other hand, according to the to the advantage of the large-scale manufacture. method of this invention all the raw materials are em- The completion of the reaction can be readily judged ployed stoichiometrically and the reaction velocity is high.

Further, as the resultant solution is neutral when the reby the change of the pH in the liquid phase of the reacaction is completed and does not contain free caustic soda tion mixture and in the meantime the reaction velocity is extremely high and the reaction is completed in a few as impurity, the purification can be achieved very easily. hours even when carried out at normal temperature; it Moreover, according to the old method the reaction solucan be further shortened by heating. tion, which is alkaline, must be repeatedly washed with However, when heated excessively the product obtained water until it becomes neutral in order to speed up the is of a less desirable quality namely heavy and hard, and reaction and to purify the reaction mixture; as a consethe acid-neutralizing capacity is also lowered. It is therequence, silioic acid and aluminum are washed away in fore desirable that the heating temperature does not exceed large quantities, thereby automatically lowering the yield 70 C. After the completion of the reaction, the reaction and causing the change in composition, while according mixture is filtered, washed with water to remove the imto the method of this invention, as the reaction process purities produced a by-produet, dried at 105 110 C., nd is quite different and the constituents are never washed pulverized. Thus, the magnesium aluminosilicate corresaway, not only is the yield increased, but also the componding to a composition of MgO-Al O w2SiO-xH O is position can be kept constant, so that it becomes very easy obtained as a white amorphous powder. to control the quality.

As stated above, according to the method of this invention the magnesium aluminosilicate of the novel structure having exactly the same components and effects as the old product, can be very easily and economically produced and accordingly this invention is considered to bring about an important improvement in the process for the manufacture of magnesium aluminosilicate for medical The magnesium alminosilicate obtained by the process of this invention is a compound of a novel chemical structure as mentioned above as it is apparent from the reaction process; furthermore it is dissolved almost com- EXAMPLE 1 pletely in 0.1 N hydrochloric acid and has an excellent acid-neutralizing capacity and superior buffering effect 203 of magnesium Chloride of the q y used as compared with the product obtained by the old method. food additive containing 46 percent MgCl is dissolved The following table shows the comparison between in 600 ml. of water, to which 96 g. of caustic soda disboth products as to the acid consuming power of 1 gm. solved in 250 ml. of water is added with stirring, and a each of the products as well as the results of Fuchs test. solution comprising 50 ml. of water with 207 g. of I18 Aeid- Fuchs test (ph value) consuming Time power ml. (min) 1 3 5 10 20 30 50 60 70 New product--. 240 pH 3.4 3.55 3.55 3.6 3.4 3.2 3.1 3.0 2.7 1.7 Old product 235 pH 3.3 3.5 3.6 3.5 3.4 3.2 3.1 3.0 2.9 1.9

In this way, the product having absolutely the same No. 3 sodium silicate is further added and is then vigorproperties as the old one is obtained by the process of this ously stirred to produce basic sodium magnesium silicate invention, but as compared with the old method the cost (which is designated as Slurry A). Ssecondly, 593 g. of of raw materials is remarkably reduced, the time required 115 Special N0. 1 aluminum sulfate containing 17.2 perto complete the reaction is considerably shortened, the cent A1 0 dissolved in 1,700 ml. of water is slowly added purification becomes simple and easy, the yield is imwith stirring to 216 g. of caustic soda dissolved in 600 ml. proved and no variation of the composition of the final of water, to which ml. of water added to 207 g. of product is brought about. It is for this reason that the JIS No. 3 sodium silicate (Na O 9%, SiO 29%) is process of this invention is considered as a remarkable slowly added and is then vigorously stirred to produce improvement both from the viewpoint of the quality contetrabasi di l i ili t hi h i d i t d as trol, and the lowering of manufacturing costs. This is 50 Slurry B). Mix Slurry A with Slurry B and mix while shoWn y the following ahaiysis of Costs of materials and vigorously stirring for 3 hours at normal temperature. The procedural expenses. thus obtained white gel-like precipitate is washed by de- Aeoordihg to the method of this invention, the amount cantation to remove free alkali, mirabilite (sodium sulof caustic soda needed to obtain 1 mol of the magnesium f t di hl id m d d as reaction b d aluminosilicate from the aluminum salt employed as raw ucts Th id i fil d d d i d at 105 to 110 C material is 4 mols, Whereas it is 8 mois according to the and 340 g. of white powder of fine particle size is obtained old method as is shown in the reaction equations referred as h fi l product h k ratios f o to 1 0 to to above; thus the amount of caustic soda standing first 10 i hi product were approximately 1;1;2 in the cost of the raw materials for the manufacture of the compound here discussed, can be reduced to half the EXAMPLE 2 amount needed in the old method, thereby lowering the cost of the raw materials remarkably. Further, it is a shortcoming of the old method which is always carried out in alkaline medium with a large quantity of the caustic soda being produced as by-product as the reaction, proceeds' amel 4 mols er 1 mol of the desired roduct,

that an elabo rate process is needed for completely elim- Water Is 9 added wlth Surfing Thereafter inating the by-product by successive washing operation compnsuig i HS 3 Sodmn? slhcate before the reaction is concluded. Moreover, the magne- .(Nazo /b with 4 of Water is pourfid sium aluminosilicate accumulated as precipitate, is of heated and surfing congmued for five While superfine particle size, therefore, very slow in the sedikeepmg the temperature at 60 when the reaction mentation rate; besides, Since it has a Very Strong adsorp ture becomes neutral, allow to cool and to stand, withtive power, it adsorbs the 'by-products produced during (how the supernatant fluid and Wash the White gel-like the reaction process, especially the caustic soda, thus reprecipitate y deeehtetioh to relhoVe the impurities; thell quiring again a huge volume of water and many hours the mass is dried at to C. whereby 350 g. of a 203 g. of magnesium chloride of the quality used as food additive, containing 46 percent MgCl and 593 g. of 118 Special N0. 1 aluminum sulfate containing 17.2 percent Al O are dissolved in 2,300 ml. of water, to which a solution comprising 272 g. of caustic soda with 800 ml.

5 white powder of fine particle size is obtained as the final product.

What we claim is: 1. A novel magnesium aluminosilicate of the formula of basic sodium magnesium silicate is obtained by adding 7 an aqueous solution of sodium hydroxide to a water soluble magnesium salt, equivalent to 1 mol of MgO, and reacting it with an aqueous solution of sodium silicate equivalent to 1 mol SiO and the slurry of dibasic aluminum silicate is obtained by adding an aqueous sodium hydroxide solution to a water soluble aluminum salt equivalent to 1 mol A1 0 and reacting it with an aqueous sodium silicate solution equivalent to 1 mol SiO whereby the total Na O content will be 3 mols.

4. A novel magnesium aluminosilicate of formula 5. The process for the production of the compound according to claim 1 which consists of heating the compound of formula Mg(OH) -SiO -A1(OH) -SiO -AI(OH) at a temperature of 105-110 C.

References Cited UNITED STATES PATENTS 3,032,394 5/1962 Ishino et a1. 23110 FOREIGN PATENTS 614,384 2/1961 Canada.

20 OSCAR R. VERTIZ, Primary Examiner H. S. MILLER, Assistant Examiner US. Cl. X.R. 231l3; 424l54 

